1. Technical Field
This invention relates generally to a method and apparatus for separating valuable material from unwanted material in a mixture, such as a pulp slurry.
2. Description of Related Art
In many industrial processes, flotation is used to separate valuable or desired material from unwanted material. Traditionally, the flotation process utilizes a specific mineral collector with a hydrophobic tail which allows the collector-mineral pair to attach to an air bubble.
In particular, current flotation processes typically use bubbles to provide a separation capability by utilizing the buoyancy of air. In such processes, a mixture of water, valuable material, unwanted material, chemicals and air may be placed into a flotation cell. Through chemical reactions desired particles are attached to a bubble, and the bubble is utilized to float the particles to the top of a tank while the other undesired material sinks to the bottom. The chemicals are used to make the desired material hydrophobic, and the air is used to carry the material to the surface of the flotation cell. When the hydrophobic material and the air bubbles collide they become attached to each other. The bubble rises to the surface carrying the desired material with it.
However, the performance of the flotation cell is dependent on the air bubble surface area flux in the collection zone of the cell. The air bubble surface area flux is dependent on the size of the bubbles and the air injection rate. Controlling the air bubble surface area flux and the bubble size distribution has traditionally been very difficult. This is a multivariable control problem and there are no dependable real time feedback mechanisms to use for control.
For these reasons, there is a need in the industry to provide a better way to separate valuable material from unwanted material, e.g., including in such a flotation cell, so as to eliminate problems associated with using air bubbles in such a separation process.
Furthermore, different methods have been developed which leverage engineered materials for separation. For example, through the use of an engineered material that attracts the particles a variety of separation means can be used, which can be much more easily controlled and can lead to a more efficient recovery process.